1. Field of the Invention
The invention disclosed and described herein relates to steam generators. More particularly the apparatus and method of employment herein disclosed relates to an improved design for a water tube boiler and steam generator which provides for improved separation of steam from residual water and enhanced protection from overheating of water tubes. The unique inclined design with curved end portions can be employed in any number of fields using steam including driving steam engines, for process steam, for steam heating, for hospital sterilizers, for most commercial power plants, for nuclear generators using steam boilers, or in any application where steam is employed.
2. Prior Art
Water-tube style boilers for steam generation have been in use for decades and generally consist of natural-circulation style and submerged style water tube boilers. Water tube boilers were developed to satisfy the demand for large quantities of steam at pressures and temperatures far exceeding those possible with fire-tube boilers.
Water tube boilers have a low risk of disastrous explosion compared to fire box boilers or fire tube boilers, and they are space saving. They also provide for rapid steam raising and ease of transportation. However, water tube boilers have required that supply water should be substantially pure and specially treated to protect the steam tubes and may require special maintenance procedures for this reason.
Because of their safety and large production capacity for steam, water tube boilers are employed in products from steam engines to nuclear power plants and are considered an especially safe design for steam generation in a steam powered system. A wide variety of sizes and designs of water tube boilers are used in power stations, nuclear reactors, ships and factories. Well known designs such as those by Babcock and Wilcox have been in use for decades and those skilled in the art will understand the positioning and employment of the included water tube device herein, in proper communication with a heat source, for use in all such boilers.
Heating the water tubes of a water tube boiler or steam generator requires that fuel is burned inside a furnace, creating hot gas. The hot gases are communicated to the water tubes in various ways known in the art to heat up water in the steam-generating tubes.
Submerged water-tube boilers generally employ a means to heat water or fluid in the steam generator. The heat from fossil fuels, nuclear power, natural gas, or other sources, is communicated to a lower bank of inclined tubes through a first substantially upright header. The first or lower bank of tubes is inclined to communicate steam upwards through a plurality of the vertical headers. In such submerged boilers, the lower bank of tubes is substantially submerged in the heated water being communicated from the first upright header. Each of the lower bank of tubes communicates at an inclined end with a second substantially vertical header wherein steam rises in the second header and water will return to the reservoir below feeding the first header.
An upper bank of tubes communicating with the second header above the water line, receives the steam communicated through the second header from the lower bank of tubes, and communicates that steam through the upper bank of tubes at an inclined angle from the second substantially vertical header back to the first header. A preferred inclining angle for the first and second bank of tubes is at an angle between 11 and 15 degrees with a current especially preferred mode being substantially 12 degrees.
Various patents such as U.S. Pat. No. 309,282, (Babbitt) describe such conventional submerged water-tube steam generators and all suffer from inadequate separation of remaining water from the steam which has been communicated to the upper bank of tubes. As such, there exists a need for an improved water-tube style boiler or steam generator which both dries and separates water from the steam. Such a device should also minimize the danger of overheating the water tubes which damages the apparatus and in doing so, results in an increased power rating for the steam generator device. Such a device should provide steam for turbines and the like which is substantially free of water droplets which can severely damage turbine blades.